Duck or "утка" is feminine in Russian and so requires "моя". Google translate recently gave me the same as Duolingo. Google translate often has errors, as it has a tendency to translate word by word until someone corrects it. https://en.wiktionary.org/wiki/%D1%83%D1%82%D0%BA%D0%B0 Scroll down to the Russian word "утка", but I did find it fun that in Macedonian the same word "утка" is used for a different bird, the owl.
у́тка (útka) [ˈutkə] f anim (genitive у́тки, nominative plural у́тки, genitive plural у́ток) "duck; canard; bedpan; cleat": Inherited from Old East Slavic уты (uty), from Proto-Slavic *ǫty, from Proto-Indo-European *h₂énh₂ts. Baltic cognates inclde Lithuanian ántis, Old Prussian antis. Further cognates with Dutch eend (“duck”), German Ente (“duck”), Ancient Greek νῆττα (nêtta), Latin anas, Spanish ánade, Sanskrit आति (ātí, “aquatic bird”).